A draft document Metadata Framework for Internet Media Guides: Metadata Envelope has been submitted to the IETF MMUSIC Working Group, together with an XML Schema for the IMG transfer envelope. The IETF Multiparty Multimedia Session Control Working Group was chartered to "develop protocols to support Internet teleconferencing and multimedia communications, focusing upon revisions of current protocols in the light of implementation experience and additional demands that have arisen from other WGs (such as AVT, SIP,SIPPING, and MEGACO), and upon delivery mechanisms for IMGs, generalizing its work on session announcement and discovery protocols (SAP, RTSP, SIP)." An Internet Media Guide (IMG) is "a collection of multimedia session descriptions expressed using Metadata Envelopeor similar session description format used to describe a collection of multimedia sessions. The purpose of the IMG metadata is to provide machine- and human-readable information describing the files, resources and multimedia programs available for streaming or downloading via multicast or unicast. IMG metadata is encapsulated into an IMG transfer envelope before it is passed to an IMG transport protocol, such as MUPPET. The purpose of the transfer envelope is to provide independence of metadata formats from transport protocols, and to enable versioning, updating and expiring of transmitted metadata." Appendix A of the MMUSIC WG's Session Description and Capability Negotiation (SDPng) draft provides the formal syntax specifications in the form of an SDPng Base DTD and SDPng XML-Schema Specification. The SDPng protocol addresses multiparty multimedia conferences, being intended for two-way negotiation and unidirectional delivery; its XML Schema will be extended to harmonize with the XML Schema for the IMG Transfer Envelope.

Bibliographic Information

A Metadata Framework for Internet Media Guides: Metadata Envelope. By Juha-Pekka Luoma (Nokia), Jani Peltotalo (Tampere University of Technology, Finland), and Sami Peltotalo (Tampere University of Technology, Finland). Appendix A. XML Schema for the IMG Transfer Envelope; Appendix B. Example of an IMG Transfer Envelope. IETF MMUSIC Working Group, Internet-Draft. Reference: 'draft-luoma-mmusic-img-metadata-envelope-00'. December 9, 2003, expires: June 8, 2004. An XML schema for the IMG transfer envelope is defined in Appendix A, providing a wrapper that can be used for encapsulating an IMG block before transmission. Appendix B provides a simple example of using this wrapper for IMG metadata.

Previously published: Session Description and Capability Negotiation (SDPng). By Dirk Kutscher, Joerg Ott,, and Carsten Bormann (TZI, Universitaet Bremen, Germany). IETF MMUSIC Working Group, Internet-Draft. Reference: 'draft-ietf-mmusic-sdpng-07.txt'. October 27, 2003, expires: April 26, 2004. Summary of SDPng XML-Syntax: The SDPng base specification defines the following XML element types that reside in the SDPng namespace designated by the namespace name "http://www.iana.org/sdpng": sdpng, cap, def, cfg, component, alt, constraints, info. Appendix A.1 provides an XML DTD that specifies the content model of the SDPng base elements.

IMG Metadata Envelope Summary

This document defines the transfer envelope for Internet Media Guides (IMGs). IMG metadata describes files, resources and multimedia programs available for streaming or downloading via multicast or unicast. IMG metadata is encapsulated into, or associated with, an IMG transfer envelope before actual transport. The transfer envelope is a structure providing independence between IMG transport protocols and different metadata formats. The IMG transfer envelope may be structured for example as a wrapper based on the Extensible Markup Language (XML) syntax.

The scope and background of the work on Internet Media Guides have been described in the IMG requirements and IMG framework specifications.

It shall be possible to provide signing and encryption to the IMG transfer envelope, limiting the capability of any intermediaries between the original IMG sender and the IMG receiver to read and modify IMG transfer envelope fields and the IMG block associated with it. Signing, encryption or both can be applied to the whole transfer envelope or just to parts of it.

IETF Multiparty Multimedia Session Control Working Group

The MMUSIC Working Group was chartered to develop protocols to support Internet teleconferencing and multimedia communications. These protocols are now reasonably mature, and many have received widespread deployment. The group is now focussed on the revisions of these protocols in the light of implementation experience and additional demands that have arisen from other WGs (such as AVT, SIP,SIPPING, and MEGACO).

Multimedia communications protocols use a common platform for expressing media and session descriptions. This is the Session Description Protocol, SDP. The many uses of SDP have led to (requests for) numerous extensions and have led to recognition of several flaws in the protocol design. In spite of these, it is widely deployed. To support this current deployment, MMUSIC will revise SDP suitable for publication as a Draft Standard RFC...

An Internet Media Guide (IMG) is a collection of multimedia session descriptions expressed using SDP, SDPng or some similar session description format. It is used to describe a collection of multimedia sessions (e.g., television programme schedules). The IMG must be delivered to a potentially large audience, who use it to join a subset of the sessions described, and who may need to be notified of changes to the IMG.

MMUSIC will investigate work on delivery mechanisms for IMGs, generalizing its work on session announcement and discovery protocols (SAP, RTSP, SIP). We will investigate and document requirements for IMG delivery mechanisms, and identify the requirements that these delivery mechanisms impose on the session description formats used by the IMG. We will then work to produce a framework document outlining the use of (existing) protocols to create an IMG delivery infrastructure. After successful completion of these initial milestones for IMG delivery, the MMUSIC working group will decide whether or not MMUSIC is the proper place to pursue any needed mechanisms for IMGs, and if so, recharter accordingly.

The MMUSIC work items will be pursued in close coordination with other IETF WGs related to multimedia conferencing and IP telephony (AVT, SIP, SIPPING, IPTEL, MEGACO). Where appropriate, new separate working groups may be split off..." [from the WG Charter]